Project 10073 Record Card and Related Correspondence — Seattle, Washington, 11 May 1952

On May 11, 1952, at approximately 0120 PST, a significant aerial event occurred over Seattle, Washington. Numerous witnesses, including a Northwest Airlines pilot and co-pilot, as well as local police officers, reported observing a vivid blue, sphere-shaped object with a tail, traveling from south to north. The object was described as performing a steep dive before exploding in a brilliant flash, which was followed by a tremendous roar and a tremor or shock wave that lasted approximately nine seconds. The event caused widespread alarm, rattling doors and windows and jamming local police and newspaper switchboards with calls from citizens who feared an earthquake or an explosion of an atomic bomb.

The Air Defense Command and the 25th Air Division (Defense) at McChord Air Force Base initiated an immediate investigation. Despite the intensity of the event, no radar installations in the Pacific Northwest network detected the object. Col. T. Allan Bennett, commanding officer of the 25th Air Force Defense Division, stated that the object was unlikely to be an aircraft or guided missile. Several experts, including Dr. Fred L. Whipple of Harvard University and Prof. Gerard Kuiper of Yerkes Observatory, provided commentary suggesting the phenomenon was a large meteor that disintegrated in the lower atmosphere. Local astronomers were contacted to verify this conclusion, and they confirmed their belief that the object was a meteor. A search for physical fragments was conducted by these astronomers, though no pieces were recovered. The official Air Intelligence Information Report concluded that the object was a meteor, though the file was initially kept open to allow for the possibility of finding confirming physical evidence. The incident remains a documented case of a high-visibility aerial event that was ultimately attributed to a natural astronomical phenomenon.